The present invention relates to a controller of an industrial vehicle, an industrial vehicle, and a control method for an industrial vehicle.
In some conventional industrial vehicles, such as loading vehicles, an engine drives a traveling mechanism and mechanisms (including a loading actuator) other than the traveling mechanism, which causes the industrial vehicle to travel (see, for example, Japanese Laid-Open Patent Publication Nos. 2004-11469 and 2004-359414).
In an industrial vehicle and a control method for the industrial vehicle described in Japanese Laid-Open Patent Publication No. 2004-11469, the engine speed is controlled in correspondence with the operational state of the industrial vehicle. Specifically, such controlling is performed with reference to different information including the operation amount of a loading lever, the depression amount of an accelerator pedal, and the depression amount of a clutch pedal. This suppresses gunning of the engine that generates noise, while simplifying the configuration of the industrial vehicle.
In an industrial vehicle and a controller of an industrial vehicle described in Japanese Laid-Open Patent Publication No. 2004-359414, it is determined that the industrial vehicle is in a process of loading if a vehicle speed detecting portion detects that the vehicle speed is zero. In this case, the controller operates to maximize the shaft torque of the engine. This ensures the engine torque needed for loading of the industrial vehicle even in a dark environment, although the speed of the industrial vehicle is limited in correspondence with the amount of light in the environment.
However, in the industrial vehicle and the control method for the industrial vehicle of Japanese Laid-Open Patent Publication No. 2004-11469, controlling of the engine speed for suppressing the gunning of the engine is performed in correspondence with a priority selected from the operational state of the loading lever, that of the accelerator pedal, and that of the clutch pedal. In other words, such controlling is performed only in a range up to an upper limit of the engine speed that is determined by the traveling performance of the industrial vehicle and in correspondence with the operational state of the loading lever or the accelerator pedal or the clutch pedal. Accordingly, the control method and the industrial vehicle do not sufficiently satisfy a requirement that the engine should be controlled in such a manner as to ensure maximum advantage of the engine performance in correspondence with the operational state of the industrial vehicle.
Further, in the industrial vehicle and the controller for the industrial vehicle described in Japanese Laid-Open Patent Publication No. 2004-359414, in which the engine torque necessary for loading in the dark environment is ensured, determination that the industrial vehicle is in a loading process depends solely on detection that the vehicle speed is zero. Therefore, efficient controlling of the engine is limited to the operational state (condition) of the industrial vehicle in which the vehicle speed is zero. Accordingly, like the control method and the industrial vehicle of Japanese Laid-Open Patent Publication No. 2004-11469, the controller and the industrial vehicle of this document do not sufficiently satisfy the above-described requirement.